In-flight refueling (or air-to-air refueling) is an important method for extending the range of aircraft traveling long distances over areas having no feasible landing or refueling points. Although in-flight refueling is a relatively common operation, especially for military aircraft, the aircraft to be refueled (e.g., the receiver aircraft) must be precisely positioned relative to the tanker aircraft in order to provide safe engagement while the fuel is dispensed to the receiver aircraft. The requirement for precise relative spatial positioning of the two rapidly moving aircraft makes in-flight refueling a challenging operation.
There are currently two primary systems for in-flight refueling. One is a hose and drogue system, which includes a refueling hose having a drogue disposed at one end. The hose and drogue are trailed behind the tanker aircraft once the tanker aircraft is on station. The pilot of the receiver aircraft then flies the receiver aircraft to intercept and couple with the drogue for refueling. Another existing system is a boom refueling system. The boom refueling system typically includes a rigid boom extending from the tanker aircraft, with a probe and nozzle at its distal end. The boom also includes airfoils controlled by a boom operator stationed on the refueling aircraft. The airfoils allow the boom operator to actively maneuver the boom with respect to the receiver aircraft, which flies in a fixed refueling position below and aft of the tanker aircraft.
One approach to addressing the challenge associated with precisely positioning the tanker aircraft relative to the receiver aircraft is to automate the positioning process. For example, one existing arrangement for boom refueling systems includes cameras housed in the tanker aircraft to determine the distance between the receiver aircraft and the tip of a refueling boom carried by the tanker aircraft. The system can then be used to automatically control the position of the boom to mate with a corresponding refueling receptacle of the receiver aircraft. The system can be configured to allow the boom operator to take control of the movement of the boom, for example, if the automatic system malfunctions or if for any reason the refueling boom must be directed away from the receiver aircraft. However, the applicability of this system has been limited to certain boom-outfitted tanker aircraft and can in some cases significantly impact the cost of such aircraft.